Inter- and Transdisciplinary Sessions
Disciplinary sessions AS–GM
Disciplinary sessions GMPV–TS

Session programme


BG – Biogeosciences

Programme group chair: Giuliana Panieri

BG4 – Marine and Aquatic Biogeosciences

Programme group scientific officers: Helmuth Thomas, Lutz Merbold


The coastal ocean has been increasingly recognized as a dynamic component of the global carbon budget. This session aims at fostering our understanding of the roles of coastal environments and of exchange processes, both natural or perturbed, along the terrestrial / coastal sea / open ocean continuum in global biogeochemical cycles. During the session recent advancements in the field of coastal and shelf biogeochemistry will be discussed. Contributions focusing on carbon and nutrient and all other element's cycles in coastal, shelf and shelf break environments, both pelagic and sedimentary, are invited.

This session is multidisciplinary and is open to observational, modelling and theoretical studies in order to promote the dialogue. The session will comprise subsections on coastal carbon storage, and on benthic biogeochemical processes.

This year the session comprises a subsection focusing on the Franco-German “Make Our Planet Great Again” (MOPGA) research initiative, which uses Earth system science to understand climate change and its impacts:
At the 2015 Paris COP21 climate conference, 195 countries committed to reduce their greenhouse gas emissions and make efforts to significantly limit man-made global warming to below 2°C above pre-industrial levels. France and Germany joined forces in this fight against global warming by creating the “Make Our Planet Great Again” research initiative covering research in Earth system science that aims to better understand climate change and its impacts on natural and socio-economic systems. In this interdisciplinary session, we welcome data- and model-based research undertaken within, but also outside this international initiative, that provides new insights into the mechanisms of past, present and future climate changes and the associated impacts on the oceans, the cryosphere, coastal regions, and terrestrial systems. Innovative research contributions that can lead towards the ultimate goals of the Paris Agreement ranging from basic research to solution-oriented research are also encouraged.

Co-organized by OS2
Convener: Helmuth Thomas | Co-conveners: William Austin, Alberto V. Borges, Arthur CapetECSECS, Craig SmeatonECSECS
| Attendance Wed, 06 May, 14:00–18:00 (CEST)

Permafrost thaw is expected to amplify the release of previously frozen material from terrestrial into aquatic systems: rivers, lakes, groundwater and oceans. Current projections include changes in precipitation patterns, active layer drainage and leaching, increased thermokarst lake formation, as well as increased coastal and river bank erosion that are further enhanced by rising water temperatures, river discharge and wave action. In addition, subsea permafrost that formed under terrestrial conditions but was later inundated might be rapidly thawing on Arctic Ocean shelves. These processes are expected to substantially alter the biogeochemical cycling of carbon but also of other elements in the permafrost area.
This session invites contributions on the mobilization of terrestrial matter to aquatic systems in the permafrost domain, as well as its transport, processing and potential interaction with autochthonous, aquatic matter. We encourage submissions focusing on organic and inorganic carbon as well as on other elements such as nitrogen, phosphorus, silica, iron, mercury and others, from all parts of the global permafrost area including mountain, inland, coastal and subsea permafrost, on all spatial scales, in the contemporary system but also in the past and future, based on field, laboratory and modelling work.

Public information:
The session will follow a loose sequence from permafrost soils to lakes, rivers, and the Arctic Ocean, closing with Arctic Ocean methane (see the list in session materials). Welcome!

Co-organized by CR4/HS13
Convener: Birgit WildECSECS | Co-conveners: Lisa BröderECSECS, Örjan Gustafsson
| Attendance Fri, 08 May, 10:45–12:30 (CEST)

Aquatic sediments are ecologically diverse and important environments, which shelter and support a variety of benthic animals and plants. Active reworking and ventilation by macrobenthic communities control the physical structure and biogeochemistry of sediment by redistribution of solids (e.g. organic carbon sources), solutes (e.g. oxygen), and microorganisms. Examples vary in scale and effect, including oxygen entrainment into riverbeds by nesting salmon, rapid bioirrigation of deep burrows by benthic invertebrates, large-scale sediment remodelling by tunnelling crustaceans (bioturbation), and oxidation of metals in the rhizosphere of macrophytes. Much of our knowledge on sediment biogeochemistry, hydrodynamics and geomicrobiology is derived from studies on undisturbed sediments, yet the majority of sediments are in some way affected by the macrobenthos. We therefore aim to gather novel research that links physico-chemical and microbial properties of the sediment to its (macro)biological community. This session invites contributions describing interactions between benthic fauna and the sediment, with emphasis on sediment biogeochemistry, hydrodynamics, geomicrobiology or molecular interactions. We aim to balance research that is field-, laboratory- and computational-focussed.

Co-organized by SSP4
Convener: Adam KesslerECSECS | Co-conveners: Erik Kristensen, Alexa WredeECSECS
| Attendance Wed, 06 May, 08:30–10:15 (CEST)

The last two decades have brought major technological advancements in characterisation of aquatic organic matter with spectroscopic and chromatographic methods and collection of water quality data at high spatial and temporal resolution with automated in situ instruments. The aim of this session is to demonstrate if and how this methodological advancement improves our understanding of dominant hydrochemical and ecological processes in aquatic environments controlling the fate of organic matter, nutrients and other pollutants.

Specifically, our ability to characterise different fractions of natural organic matter has increased thanks to a range of analytical methods e.g. fluorescence and absorbance spectroscopy, mass spectrometry and chromatography combined with new data mining tools (self-organising maps, PARAFAC analysis). Matching the water quality measurement interval with the timescales of hydrological responses (from minutes to hours) thanks to automated in situ wet-chemistry analysers, optical sensors and lab-on-a-chip instruments has led to discovery of new hydrochemical and biogeochemical patterns in aquatic environments e.g., concentration-discharge hysteresis and diurnal cycles. We need to understand further how hydrochemical and ecological processes control those patterns, how different biogeochemical cycles are linked in aquatic environments (e.g., carbon, phosphorus, nitrogen, sulphur and iron) and how human activities disturb those biogeochemical cycles by emitting excess amounts of nutrients to aquatic systems. In particular, there is a growing need to better characterise the origins, delivery pathways, transformations and environmental fate of organic matter and nutrients in aquatic environments along with identification of robust numerical tools for advanced data processing and modelling.

Previously in this session:
2019 https://meetingorganizer.copernicus.org/EGU2019/session/32089
2018 https://meetingorganizer.copernicus.org/EGU2018/session/26401
2017 http://meetingorganizer.copernicus.org/EGU2017/session/24958
2016 http://meetingorganizer.copernicus.org/EGU2016/session/20013
2015 http://meetingorganizer.copernicus.org/EGU2015/session/17101
2014 http://meetingorganizer.copernicus.org/EGU2014/session/15261

Co-organized by HS10
Convener: Magdalena Bieroza | Co-conveners: Andrea Butturini, Bethany FoxECSECS, Diane McKnight, Michael Rode
| Attendance Wed, 06 May, 10:45–12:30 (CEST)

Due to the growing pressures on marine resources and the ecosystem services demand, the interest of scientific and politic world is moving to ensure marine ecosystems conservation and environmental sustainable development providing policies to meet the UN 2030 Agenda Goal 14 in order to “Conserve and sustainably use the oceans, seas and marine resources for sustainable development”. To act against the decline of the ocean health and to create a framework of stakeholders, the UN proposed the establishment of the “Decade of Ocean Science for Sustainable Development” able to bring regional knowledge and priorities together in an international action plan. Anthropogenic activities could have an impact on the marine environment and affect the ecosystem equilibrium. The marine environment is a dynamic, sensitive and fragile area in which it is advantageous to apply new methodologies and observing methods to increase the quantity and quality of the data. Since ocean dynamical affect the dispersion of pollutants such as chemicals, plastics, noise and invasive species, the ecosystems status should be analyzed through the study of abiotic variables distribution at a proper spatio-temporal scale. To analyze the ocean environmental quality, a large amount of data obtained by global observation systems (e.g. GOOS, EMODNET) is needed, which requires the development of cost-effective technologies for integrated observing systems and to support the study of, e.g., biological variables. The session focuses on marine ecosystems and biogeochemistry, technological developments for the study of abiotic and biotic factors, with a focus on anthropogenic impacts. Multidisciplinary approaches using data coming from multiple sources are encouraged. Integration of mathematical models, in-situ and remote observations is suggested with the aim to develop methods, technologies and best practices to maintain, restore and monitor biodiversity and to guarantee sustainable use of marine resources. The following topics will be discussed: effects of pollution on biota considering their natural and anthropogenic sources; short-term and long-term impact of economic activities on the seabed; potential remediation of diverse anthropogenic alterations on the seafloor; global change effects on marine ecosystem; new technology development; advanced methods for collection, data processing, and information extraction; benthic and pelagic community dynamics; economic evaluation of natural capital.

Co-organized by BG4
Convener: Marco Marcelli | Co-conveners: Paola Del Negro, Roberta FerrettiECSECS, Xiaoxia Sun, Markus Weinbauer, Sebastiaan van de VeldeECSECS, Sarah ParadisECSECS
| Attendance Fri, 08 May, 14:00–15:45 (CEST), Attendance Fri, 08 May, 16:15–18:00 (CEST)

The rapid decline of Arctic sea ice in the last decade is a dramatic indicator of climate change. The Arctic sea ice cover is now thinner, weaker and drifts faster. The ocean is also changing; the volume of freshwater stored in the Arctic and has increased as have the inputs of coastal runoff from Siberia and Greenland. Concurrently inflows from the Atlantic and Pacific Oceans have warmed. As the global surface temperature rises, the Arctic Ocean is speculated to become seasonally ice-free in the 21st century, which prompts us to revisit our perceptions of the Arctic system as a whole. What could the Arctic look like in the future? How are the present changes in the Arctic going to affect the lower latitudes? What aspects of the changing Arctic should future observations, remote sensing and modelling programmes address? The scientific community is investing considerable effort in making the current knowledge of the physical and biogeochemical properties of the Arctic more systematic, in exploring poorly understood coupled atmosphere-sea-ice-ocean processes to improve prediction of future changes in the Arctic.

In this session, we invite contributions from a variety of studies addressing the recent past, present and future Arctic. We encourage submissions examining interactions between the ocean, atmosphere and sea ice and on studies linking changes in the Arctic to the global ocean. Submissions with a focus on emerging cryospheric, oceanic and biogeochemical processes and their implications are particularly welcome.

The session promotes results from current Arctic programmes and discussions on future plans for Arctic Ocean modelling and measurement strategies, and encourage submissions on the results from the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC).

Public information:
Session structure file is back.


Co-organized by AS4/BG4/CL2/CR6
Convener: Yevgeny Aksenov | Co-conveners: Paul A. Dodd, Céline Heuzé, Krissy Reeve
| Attendance Thu, 07 May, 08:30–12:30 (CEST)

Decreasing sea-ice coverage, increasing permafrost-derived inputs and increasing ice sheet and glacier discharge will continue to affect high latitude environments in the coming decades under all future climate scenarios. Such changes at the interface between the ocean and the cryosphere raise questions about the downstream effects in marine ecosystems, as increased meltwater discharge is likely to impact not only coastal hydrology but also biogeochemistry, sediment transport and ecosystem services such as fisheries and carbon sequestration. However, the impact of increasing melt on fjord and coastal environments is poorly constrained, impacting our ability to make predictions regarding the consequences of future climate change. In order to understand the effect of changing cryosphere-derived inputs on high latitude fjords and marine coastal environments, knowledge concerning the physical and biochemical perturbations occurring in the sea ice and water column and the structure, function and resilience of affected ecosystems must be integrated. In this session we explicitly welcome cross-disciplinary attempts to understand how far reaching the effects of sea-ice, permafrost derived material and glacial changes are on marine biogeochemistry, productivity, biodiversity, and ecosystem services. Topics may include, yet are not limited to, the effect of sea-ice, permafrost, and glacier discharge on sea-ice and water column structure, primary and secondary production, community structure, macronutrient and micronutrient availability, microbial processes, the carbonate system, and the biological carbon pump. Modelling experiments, and studies based on long-term observational records including sediment traps and proxy reconstructions from marine sediment cores are also welcome.

Co-organized by BG4/CL4/OS3
Convener: Sofia Ribeiro | Co-conveners: Jade HattonECSECS, Mark HopwoodECSECS, Letizia Tedesco, Anna Pienkowski, Jonathan HawkingsECSECS, Susann Henkel, Hong Chin NgECSECS
| Attendance Thu, 07 May, 16:15–18:00 (CEST)

In recent years the interaction between the ocean and the cryosphere in the marginal seas of the Southern Ocean has become a major focus in climate research. Questions such as "Why has Antarctic sea ice only recently begun to decline?", "What controls the inflow of warm water into ice shelf cavities and how does it interact with the ice?", and “What are the dominant processes in ice-ocean boundary layers?” have attracted scientific and public attention. Recent advances in observational technology, data coverage, and modeling provide scientists with a better understanding of the mechanisms involving ice-ocean interactions of various types in the far South. Processes on the Antarctic continental shelf have been identified as missing links between the cryosphere, the global atmosphere and the deep open ocean that need to be captured in large-scale and global model simulations. Similarly, our limited knowledge of processes in ice-ocean boundary layers, such as heat and salt fluxes that control the melt rate, has been identified as a limitation on our ability to fully understand, let alone parameterize melting and freezing at interfaces between the ocean and ice shelves, icebergs, glaciers, and sea ice.

This session includes studies of the Southern Ocean's marginal seas including the Antarctic continental shelf and ice shelf cavities, as well as process studies with a particular focus on ice-ocean boundary layers and on all scales, from the ice-ocean interface to local to basin-scale to circumpolar. Physical and biogeochemical interactions between ice shelves, sea ice and the open ocean will be presented, along with their impacts on the greater Antarctic climate system. Presentations include theoretical studies as well as those based on in-situ observations, remote sensing, and process-scale, regional and global models. While the primary focus of the session is on ice-ocean interactions, we also includes contributions on ice-covered freshwater lakes.

Public information:
16:15-16:50 Characteristics of Polar Seas and connection with ice shelves and the open ocean
Chairs: Leo, Louis

16:15-16:20 Raquel Flynn (D2761 | EGU2020-21107)
16:20-16:25 Katherine Hutchinson (D2768 | EGU2020-112)
16:25-16:30 Roberto Grilli (D2772 | EGU2020-2984)
16:30-16:35 Chengyan Liu (D2770 | EGU2020-2319)
16:35-16:40 Ria Oelerich (D2763 | EGU2020-463)
16:40-16:45 Ute Hausmann (D2767 | EGU2020-22464)
16:45-16:50 General Discussion

16:50-17:20 Sea ice and its interaction with ice shelves and the Southern Ocean
Chairs: Nadine, Xylar

16:50-16:55 Lucile Ricard (D2765 | EGU2020-17820)
16:55-17:00 Pierre-Vincent Huot (D2780 | EGU2020-19677)
17:00-17:05 Isabelle Giddy (D2777 | EGU2020-9934)
17:05-17:10 F. Alexander Haumann (D2782 | EGU2020-22008)
17:10-17:15 Sönke Maus (D2762 | EGU2020-6039)
17:15-17:20 General Discussion

17:20-18:00 Turbulent Ice Shelf-Ocean Boundary Layers
Chairs: Irena, Xylar

17:20-17:25 Ryan Patmore (D2769 | EGU2020-10388)
17:25-17:30 Leo Middleton (D2781 | EGU2020-9112)
17:30-17:35 Louis-Alexandre Couston (D2776 | EGU2020-19054)
17:35-17:40 Carolyn Branecky Begeman (D2774 | EGU2020-10848)
17:40-17:45 Peter Davis (D2771 | EGU2020-50)
17:45-18:00 General Discussion

Co-organized by BG4/CL2/CR6
Convener: Xylar Asay-Davis | Co-conveners: Louis-Alexandre CoustonECSECS, Leo Middleton, Nadine SteigerECSECS, Irena VankovaECSECS
| Attendance Thu, 07 May, 16:15–18:00 (CEST)

The Southern Ocean around the latitudes of the Antarctic Circumpolar Current is a key region for the vertical and lateral exchanges of heat, carbon and nutrients, with significant impacts on the climate system as a whole. The role of the Southern Ocean as a sink of anthropogenic carbon and heat, and as a source of natural carbon in present and future climate conditions remains uncertain. To reduce this uncertainty, understanding the physical and biogeochemical processes underlying the Southern Ocean internal variability and its response to external forcing is critical. Recent advances in observational capabilities, theoretical frameworks, and numerical models (e.g. CMIP6 simulations) are providing a deeper insight into the three-dimensional patterns of Southern Ocean change. This session will discuss the current state of knowledge and novel findings concerning the role of the Southern Ocean in past, present, and future climates. In particular, it will address physical, biological, and biogeochemical processes, including interior ocean mixing and transport pathways, the cycling of carbon and nutrients, as well as ocean-ice-atmosphere interactions, and their wider implications for lower latitudes and the global climate.

Highlight: Solicited speaker Michael Meredith will report on the outcomes of the Polar Regions chapter of the recent "IPCC Special Report on the Ocean and Cryosphere in a Changing Climate" during this session.

Public information:
Please join our live text chat on the display items. The displays will be discussed in the order outlined in our program: https://tinyurl.com/y88p7g5o

There will be a joined virtual (video) coffee break (15:45-16:15 CEST) between sessions OS1.12 and OS1.13 as well as a follow-up online open bar (18:00- CEST). Please join us. You can find a registration link in the session program.

Co-organized by BG4/CL4
Convener: Alexander HaumannECSECS | Co-conveners: Ivy FrengerECSECS, Lavinia Patara, Christian Turney
| Attendance Thu, 07 May, 14:00–15:45 (CEST)

Ocean oxygen loss is one of the key consequences of climate change and has the potential to critically impact marine biogeochemical cycles and ecology. Current time series projections and climate models identify an unusually rapid decline in oxygen concentrations, particularly in tropical regions. However, our understanding of how stable this trend is over longer time scales, how adaptable ecosystems are, and if negative or positive feedback mechanisms exist is insufficient.

We seek to identify major gaps in knowledge helping to quantify the rate of ocean deoxygenation and its impact on both biogeochemistry and marine life. To do so, this session aims to bring together scientists from across disciplines including physical oceanography, climate modeling, biogeochemistry, and deep time experts. Our aim is not only to bring our results together but to conclude on what changes in ocean oxygen content can be identified across different ocean areas and different geological timescales.

We invite contributions that investigate ocean deoxygenation in the past, present and future ocean, and its physical, chemical and/or biological drivers, using observational or model-based approaches at regional or global scales.

Co-organized by BG4
Convener: Bastien QuesteECSECS | Co-convener: Carolin LöscherECSECS
| Attendance Tue, 05 May, 14:00–15:45 (CEST)

Over the past decades, emission reductions for air pollution abatement resulted in changes in precipitation, cloud and aerosol chemical composition, and in atmospheric deposition of anthropogenically derived nutrients to the ocean, affecting atmospheric acidity and atmospheric deposition to ecosystems.
Atmospheric acidity is central to many processes in the atmosphere and the Earth system: atmospheric chemistry, biogeochemical cycles, atmospheric deposition, ecosystems, human health, and climate. Atmospheric deposition impacts on marine productivity, oceanic carbon dioxide uptake and emissions to the atmosphere of climate active species. These oceanic emissions of reactive species and greenhouse gases influence atmospheric chemistry and global climate, and induce potentially important chemistry-climate feedbacks. Thus, air-sea fluxes of biogeochemically active constituents have significant impacts on global biogeochemistry and climate.
Despite the wide range of important effects of atmospheric acidity and air-sea exchanges, scientific knowledge gaps remain. Understanding atmospheric acidity’s levels, its spatial and temporal variability and controlling factors in the precipitation and the suspended atmospheric media, aerosols and clouds, and its multiple impacts, is an open scientific topic for research. We also still lack understanding of many of the physical and biogeochemical processes linking atmospheric deposition, atmospheric acidity, nutrient availability, marine biological productivity, and the biogeochemical cycles governing air-sea fluxes of these climate active species. Atmospheric inputs of other toxic substances, e.g., lead, cadmium, copper, and persistent organic pollutants, into the ocean are also of concern.
To address these current knowledge gaps, in this session we welcome new findings from laboratory, in-situ and remote sensing observations and atmospheric and oceanic numerical models, on the status of atmospheric acidity, the factors that affect its levels, its wide range of impacts, on atmospheric deposition of nutrients and toxic substances to the ocean, their impacts on ocean biogeochemistry, on the air-sea fluxes of climate active species and potential feedbacks to climate.
This session is jointly sponsored by GESAMP Working Group 38 on ‘The Atmospheric Input of Chemicals to the Ocean’, the Surface Ocean-Lower Atmosphere Study (SOLAS), and the International Commission on Atmospheric Chemistry and Global Pollution (iCACGP).

Co-organized by BG4/OS3, co-sponsored by SOLAS and GESAMP WG38
Convener: Parvadha Suntharalingam | Co-conveners: Maria Kanakidou, Nicole Riemer, Arvind SinghECSECS, Andreas Zuend
| Attendance Fri, 08 May, 10:45–12:30 (CEST)

The Indian Ocean is unique among the other tropical ocean basins due to the seasonal reversal of monsoon winds and concurrent ocean currents, lack of steady easterlies that result in a relatively deep thermocline along the equator, low-latitude connection to the neighboring Pacific and a lack of northward heat export due to the Asian continent. These characteristics shape the Indian Ocean’s air-sea interactions, as well as its variability on (intra)seasonal, interannual, and decadal timescales. They also make the basin and its surrounding regions, which are home to a third of the global population, particularly vulnerable to anthropogenic climate change: robust trends in heat transport and freshwater fluxes have been observed in recent decades in the Indian Ocean and Maritime Continent region. Advances have recently been made in our understanding of the Indian Ocean’s circulation, interactions with adjacent ocean basins, and its role in regional and global climate. Nonetheless, significant gaps remain in understanding, observing, modeling, and predicting Indian Ocean variability and change across a range of timescales.
This session invites contributions based on observations, modelling, theory, and palaeo proxy reconstructions in the Indian Ocean that focus on understanding recent observed and projected changes in Indian Ocean physical and biogeochemical properties and their impacts on ecological processes, links between Indian Ocean variability and monsoon systems on (intra)seasonal to interannual timescales, interactions and exchanges between the Indian Ocean and other ocean basins, natural decadal variability, and extreme events. Contributions are sought in particular that address research on the Indian Ocean grand challenges highlighted in the recent IndOOS Decadal Review, and as formulated by the Climate and Ocean: Variability, Predictability, and Change (CLIVAR), the Sustained Indian Ocean Biogeochemistry and Ecosystem Research (SIBER), and the International Indian Ocean Expedition 2 (IIOE-2) programs.

Co-organized by BG4/CL4
Convener: Caroline Ummenhofer | Co-conveners: Yan Du, Alejandra Sanchez-FranksECSECS, Jérôme Vialard
| Attendance Thu, 07 May, 08:30–10:15 (CEST)

It has been shown that regional climate change interacts with many other man-made perturbations in both natural and anthropogenic coastal environments. Regional climate change is one of multiple drivers, which have a continuing impact on terrestrial, aquatic and socio-economic (resp. human) environments. These drivers interact with regional climate change in ways, which are not completely understood. Recent assessments all over the world have partly addressed this issue (e.g. Assessment of Climate Change for the Baltic Sea region, BACC (2008, 2015); North Sea Climate Change Assessment, NOSCCA (2011); Canada’s Changing Climate Report, CCCR (2019)).
This session invites contributions, which focus on the connections and interrelations between climate change and other drivers of environmental change, be it natural or human-induced, in different regional seas and coastal regions. Observation and modelling studies are welcome, which describe processes and interrelations with climate change in the atmosphere, in marine and freshwater ecosystems and biogeochemistry, coastal and terrestrial ecosystems as well as human systems. In particular, studies on socio-economic factors like aerosols, land cover, fisheries, agriculture and forestry, urban areas, coastal management, offshore energy, air quality and recreation, and their relation to climate change, are welcome.
The aim of this session is to provide an overview over the current state of knowledge of this complicated interplay of different factors, in different regional seas and coastal regions all over the world.

Co-organized by BG4/HS12/NH10/OS2
Convener: Marcus Reckermann | Co-conveners: Ute Daewel, Helena Filipsson, Markus Meier, Markus Quante
| Attendance Thu, 07 May, 16:15–18:00 (CEST)

This session provides a platform for cross-disciplinary science that addresses the continuum of the river and its catchment to the coastal sea. We invite studies across geographical borders; from the source to the sea including groundwater, and across the freshwater-marine water transition. The session welcomes studies that link environmental and social science, address the impacts of climate change and extreme events, and of human activities on water and sediment quality and quantity, hydromorphology, biodiversity, ecosystem functioning and ecosystem services of River-Sea systems, and that provide solutions for sustainable management of the River-Sea social-ecological system.
We need to fully understand how River-Sea-Systems function. How are River-Sea-Systems changing due to human pressures? What is the impact of processes in the catchment on marine systems function, and vice versa? How can we discern between human-induced changes or those driven by natural processes from climate-induced variability and extreme events? What will the tipping points of socio-ecologic system states be and what will they look like? How can we better characterise river-sea systems from the latest generation Earth observation to citizen science based observatories. How can we predict short and long term changes in River-Sea-Systems to manage them sustainably? What is the limit to which it is possible to predict the natural and human-influenced evolution of River-Sea-Systems? The increasing demand to jointly enable intensive human use and environmental protection in river-sea systems requires holistic and integrative research approaches with the ultimate goal of enhanced system understanding.

Co-organized by BG4/GM6/NH5/OS2/SSP3, co-sponsored by IAS
Convener: Jana Friedrich | Co-conveners: Debora Bellafiore, Dietrich Borchardt, Andrea D'Alpaos, Michael Rode
| Attendance Mon, 04 May, 14:00–15:45 (CEST)

Plastic contamination has been reported in all realms of the environment from the tropics to the polar oceans. Our poor knowledge of plastics sources, pathways and hot spots of accumulation prevents an assessment of risks to ecosystems and human health and the development of appropriate mitigation strategies. In order to understand current distributions of plastics and the way they evolve in space and time, much better observations and common consistent measuring methods are required but simultaneously, observations must be systematically combined with computational models
The session aims to set up a forum for multi-disciplinary discussions to create a global picture of plastic contamination in the environment and to suggest approaches for future research, monitoring and mitigation of plastic pollutions impacts. The session will provide a platform for discussions to advise policy and industry on the best ways to assess potential harm to the environment and human health from this contaminant.
This session will draw together research on plastic contamination across all sizes of plastics from shelf seas to the deep ocean including ice covered seas. The forum will facilitate combining observations with state-of-the-art computational modelling to promote the fast advance of research and improve our understanding of how plastic pollution affects environments worldwide. We invite contributions on field and remote observations, laboratory experiments, novel modelling approaches, related scientific initiatives and projects. New ideas for citizen-science involvement and for mitigation strategies to reduce plastic contamination of the environment are especially welcome.

Co-organized by BG4
Convener: Stefanie RyndersECSECS | Co-conveners: Yevgeny Aksenov, H.G. Orr, Ilka Peeken, Anna Rubio
| Attendance Wed, 06 May, 08:30–10:15 (CEST)

Plastic pollution in freshwater systems is a widely recognized global problem with severe environmental risks. Besides the direct negative effects on freshwater ecosystems, freshwater plastic pollution is also considered the dominant source of plastic input into the oceans. However, research on plastic pollution has only recently expanded from the marine environment to freshwater systems, and therefore data and knowledge from field studies are still limited in regard to freshwater. This knowledge gap must be addressed to understand the dispersal and distribution of plastics and their fate in the oceans, as well as forming effective mitigation measures.

In this session, we explore the current state of knowledge and activities on (macro to micro) plastic in freshwater systems, including aspects such as:

• Plastic monitoring techniques;
• Case studies;
• Source to sink investigations;
• Transport processes of plastics in watersheds;
• Novel measurement approaches, such as citizen science or remote sensing;
• Modelling approaches for local and/or global river output estimations;
• Legislative/regulatory efforts, such as monitoring programs and measures against plastic pollution in freshwater systems.

Co-organized by BG4/GI6/NH8
Convener: Tim van Emmerik | Co-conveners: Daniel González-Fernández, Merel KooiECSECS, Freija Mendrik, Alice HortonECSECS, Simon Dixon, Imogen Napper, Manousos Valyrakis
| Attendance Tue, 05 May, 14:00–18:00 (CEST)

A large proportion of the global stream network comprises channels that cease to flow or dry periodically. These systems range from near-perennial rivers with infrequent, short periods of zero flow to rivers experiencing flow only episodically following large rainfall events. Intermittent and ephemeral rivers support a unique high-biodiversity because they are coupled aquatic-terrestrial systems that accommodate a wide range of aquatic, semi-aquatic and terrestrial flora and fauna. Extension and connection of the flowing stream network can affect the quantity and quality of water in downstream perennial rivers. In many arid conditions, they are the main source of fresh water for consumptive use. However, in many places intermittent and ephemeral rivers lack protection and adequate management. There is a clear need to study the hydrology, ecology and biogeochemistry of natural intermittent and ephemeral streams to characterize their flow regimes, to understand the main origins of flow intermittence and how this affects their biodiversity, and to assess the consequences of altered flow intermittency (both increased and decreased) in river systems.
This session welcomes all contributions on the science and management of intermittent and ephemeral streams, and particularly those illustrating:
• current advances and approaches in characterizing and modelling flow intermittency,
• the effects of flow in intermittent streams on downstream perennial streams,
• the factors that affect flowing stream network dynamics
• land use and climate change impacts on flow intermittency,
• links between flow intermittency and biogeochemistry and/or ecology.

Co-organized by BG4
Convener: Catherine Sefton | Co-conveners: E. Sauquet, Ilja van Meerveld
| Attendance Mon, 04 May, 14:00–15:45 (CEST)

Bayesian approaches have become increasingly popular in water quality modelling, thanks to their ability to handle uncertainty comprehensively (data, model structure and parameter uncertainty) and as flexible statistical and data mining tools. Furthermore, graphical Bayesian Belief Networks can be powerful decision support tools that make it relatively easy for stakeholders to engage in the model building process. The aim of this session is to review the state-of-the-art in this field and compare software and procedural choices in order to consolidate and set new directions for the emerging community of Bayesian water quality modellers.

In particular, we seek contributions from water quality research that use Bayesian approaches to, for example but not exclusively:
• quantify the uncertainty of model predictions
• quantify especially model structural error through, for example, Bayesian Model Averaging or structural error terms
• address the problem of scaling (e.g. disparity of scales between processes, observations, model resolution and predictions) through hierarchical models
• model water quality in data sparse environments
• compare models with different levels of complexity and process representation
• use statistical emulators to allow probabilistic predictions of complex modelled systems
• integrate prior knowledge, especially problematizing the choice of Bayesian priors
• produce user-friendly decision support tools using graphical Bayesian Belief Networks
• involve stakeholders in model development and maximise the use of expert knowledge
• use machine-learning and data mining approaches to learn from large, possibly high-resolution data sets.

Co-organized by BG4
Convener: Miriam GlendellECSECS | Co-conveners: Ibrahim Alameddine, Lorenz AmmannECSECS, Hoseung JungECSECS, James E. Sample
| Attendance Mon, 04 May, 10:45–12:30 (CEST)

The erosion, transport, temporary storage, and deposition of sediment govern the fluxes and distribution of solid mass on the surface of the Earth. The rate and extent of these mass fluxes is controlled by the complex interplay of surface processes that act across a range of spatial and temporal scales. Understanding these processes and their dependence on external forcing (e.g. climate, tectonics) and internal feedbacks (autogenic dynamics) is instrumental for constraining the cycling of sediment from source-to-sink, and to invert sedimentary archives for past environments.
A growing body of studies continues to develop a process-based understanding of the coupling between climate, tectonics, erosion, and the transport of solids across large catchments. Important insights into sediment recycling and residence time have been provided by recent advances in geochemical and geophysical techniques, highlighting the dynamic nature of sediment transport. However, many challenges remain including; (1) fully quantifying the time- and spatial scales of sediment transport, (2) tracking signals across catchments and inverting sedimentary records, and (3) assessing the importance of large and infrequent events in controlling erosion and sediment transport.
In this session we welcome field-based, experimental, and modelling studies, that (1) constrain mechanisms, rates, and scales of erosion, transport, and deposition processes, (2) analyse the influence of internal and external forcing on these processes, (3) investigate the propagation of geochemical or physical signals across the earth surface (such as changes in sedimentary fluxes, grain size distributions, cosmogenic nuclide concentrations) and (4) invert sedimentary archives to learn about past environments. Contributions across all temporal and spatial scales are welcome. We particularly encourage early career scientists to apply for this session.

Solicited presenter: Elizabeth Dingle (Simon Fraser University)

Co-organized by BG4/HS13/SSP3
Convener: Oliver FrancisECSECS | Co-conveners: Aaron BufeECSECS, Lisa HarrisonECSECS, Stefanie TofeldeECSECS
| Attendance Fri, 08 May, 10:45–12:30 (CEST)

Coastal wetland ecosystems, such as salt marshes, mangroves, seagrass beds and tidal flats, are under increasing pressure from natural and anthropogenic processes shifting climatic conditions, and are declining in area and habitat quality globally. These environments provide numerous ecosystem services, including flood risk mediation, biodiversity provision and climate change mitigation through carbon storage. Hence, the need to get a deeper understanding of processes and interactions in these environments, and how these may be altered by climate change has never been greater. This is the case for ‘managed’, restored wetlands and natural systems alike.
This session will bring together studies of coastal wetland ecosystems across climates and geomorphic settings, to enhance the understanding of ecosystem service provisioning, interactions between hydrodynamics, sediment and ecology, and identify best future management practices. Studies of all processes occurring within coastal wetlands are invited. This includes, but is not exclusive to, sediment dynamics, hydrology, hydrodynamics, biogeochemistry, morphological characterisation, geotechnical analysis, bio-morphodynamics, ecological change and evolution, impact of climate change, sea level rise, anthropogenic and management implications. Multidisciplinary approaches across spatial and temporal scales are encouraged, especially in relation to global climate change. This session aims to enhance our understanding of basic processes governing coastal wetland dynamics and to propose sustainable management solutions for contemporary environmental pressures.

Co-organized by BG4/HS13/OS2
Convener: Mark Schuerch | Co-conveners: Thorsten BalkeECSECS, Helen BrooksECSECS, Ruth Reef, Christian SchwarzECSECS
| Attendance Fri, 08 May, 16:15–18:00 (CEST)

Groundwater-surface water interfaces (e.g., hyporheic and benthic zones and riparian corridors) are integral components of the aquifer-river or aquifer-lake continuum. Interactions between groundwater and surface water lead to strong bi-directional influences between surface waters, aquifers and interconnecting hyporheic zones. A rapidly expanding number of research projects are now investigating the implications of hyporheic exchange on the transport and transformation of nutrients and contaminants within river networks, and on controls to heat, oxygen, and organic matter budgets available to microorganisms and macroinvertebrates in streambed sediments. However, there is still a need to better understand the links between physical, biogeochemical, and ecological process dynamics in groundwater-surface water interfaces and their implications for fluvial ecology or limnology, respectively. Furthermore, it is important to consider the response of hyporheic exchange fluxes to environmental and climatic controls at different spatial and temporal scales (e.g. river channel, alluvial aquifer, regional groundwater flow). We consider up- and downscaling and the development of a general conceptual framework and improved process understanding for groundwater-surface water interfaces as among the most urgent challenges of hyporheic zone research. Consequently, we particularly welcome contributions that aim to close these knowledge gaps and solicit both experimental and modelling studies with a focus on:

- The development and application of novel experimental methods to investigate physical, biogeochemical and ecological conditions at the groundwater-surface water interface in rivers, lakes, riparian corridors, and wetlands;

- Investigations of the role of hyporheic processes for the retention and natural attenuation of nutrients and pollutants, particularly with respect to impacts on surface water and groundwater quality;

- Hydrological, biogeochemical and ecological modelling approaches (e.g. transient storage models, coupled groundwater-surface water models etc.);

- Investigations of the implications of groundwater-surface water interactions for management and risk assessment frameworks with regard to the European Water Framework Directive.

Solicited contribution: Kevin Roche, Institute of Environmental Assessment and Water Research, Spanish National Research Council (CSIC)

Co-organized by BG4
Convener: Julia KnappECSECS | Co-conveners: Fulvio Boano, Jan Fleckenstein, Stefan Krause, Jörg Lewandowski
| Attendance Tue, 05 May, 14:00–18:00 (CEST)